Giorgio Tosi

In the last few years, vibrational spectroscopies have been widely applied in biology and medicine, as a synergic support to commonly used analytical and diagnostic techniques. This review summarizes the relevant researches carried out by using FTIR and Raman spectroscopy on oviparous and mammalian gametes, including human ones.

There is an imperative need to distinguish stable from unstable and vulnerable plaques because of the occurrence of thrombosis following rupture of the plaque. Imaging techniques, invasive and noninvasive, are used routinely for the assessment of visualization and quantification of this pathology, even if invasive techniques cannot be applied in the screening of atherosclerotic plaques and noninvasive imaging has low reproducibility. The aim of this review was to verify the suitability and the advantages of using vibrational spectroscopy in the study of human atherosclerotic plaques. The utilization of validated vibrational techniques in clinical trials may be of great importance for the ability to diagnose the early onset of a disease, rapidly, noninvasively and unambiguously. These techniques, by using a worldwide accepted protocol in spectral investigation of bioclinical changes in the human body, have been successfully applied to assess vulnerable plaques in ex vivo and in vivo models, constituting a potentially useful support to classical clinical imaging techniques. It is conceivable that this fingerprinting approach, with further clinical validation, is ready to be developed for use and at the disposal of commercial and easy-to-use spectrometers, equipped with catheter-based systems for the in vivo imaging of atherosclerosis plaques.

Fourier transform infrared (FTIR) microspectroscopy has been employed to investigate benign (ordinary dermal and Reed nevi), dysplastic and malignant (invasive melanoma) skin lesions through the analysis of spectral changes of melanocytes as well as in the evaluation of the presence of melanin. Hierarchical cluster analysis and principal component analysis led to a satisfactory separation of malignant from dysplastic and normal melanocytes. Also, on enlarging the clustering with spectra from Reed and dermal nevi, the multivariate analysis segregated well the spectral data into discrete clusters, allowing the obtaining of reliable average spectra for analysis at the molecular level of the main groups or components responsible for the biological and biochemical changes. The most significant spectral characteristics appear to be related to differences in secondary protein structures, in nucleic acid conformation, in intra- and intermolecular bonding. In all cases, supervised and unsupervised spectral analyses resulted in satisfactory agreement with histopathological findings.

Objective: To investigate the short-term optical, chemical and morphological changes in Invisalign appliances. Methods: One ‘as-received’ Invisalign aligner, one ‘as-received’ Invisalign aligner immersed in artificial saliva for 14 days and 10 Invisalign aligners worn by 10 randomly selected patients for 14 days were used. Fourier transform infra-red microspectroscopy was used to characterise any molecular changes on the surfaces of the appliances, spectrophotometry was used to evaluate any changes in colour and transparency, scanning electron microscopy and energy dispersive X-ray microanalysis were used to examine the surface morphology and elemental composition of deposits on the surfaces of the aligners and gas chromatography-mass spectrometry was used to identify substances released from the aligners into the artificial saliva. Results: Aligners worn for 14 days had microcracks, abraded and delaminated areas, localised calcified biofilm deposits and loss of transparency. Monomers and/or by-products were not released from the aligner suspended in artificial saliva for 14 days, which suggests that the material is chemically stable. Conclusions: Further studies are required to evaluate how intra-oral conditions may influence the optical properties and chemical stability of the aligners.

On continuing our studies on head and neck neoplasia, specimens from salivary gland tumors have been explored by using infrared microimaging spectroscopy to discern healthy from neoplastic tissues. Samples with Warthin tumor, epithelial displasia, marginal B‐cell lymphoma, low‐grade adenocarcinoma, and adenoid cystic carcinoma pathologies have been investigated by using conventional light sources. Changes were monitored at the molecular level, probing spectral markers such as Amide I and II, phosphate, nucleic acids, and carbohydrates vibrational modes. In all cases, supervised and unsupervised spectral analyses resulted in satisfactory agreement with histopathological findings. Microsc. Res. Tech., 2009.